The present disclosure applies to a landing aid device intended to provide aid with the guidance of the aircraft, to help the pilot to manually perform the flare, during a landing, just before touching the landing runway or the ground for an emergency landing.
It is known that, toward the end of the final approach with a view to landing, the aircraft is normally in a stabilized descent. After passing through a flare-triggering height, the pilot must reduce vertical speed before touching the ground to ensure the comfort of passengers and prevent any damage to the aircraft structure.
This maneuver is difficult to accomplish due to its short duration, generally in the order of five seconds for transport aircraft, during which a dynamic manoeuver close to the ground must therefore be performed. A maneuvering error may result in a hard landing or an excessively long landing distance.
Management of the flare using a head-up display (HUD) enables this risk to be reduced. In this case, the pilot guides the aircraft manually so that the speed vector of the aircraft displayed on the screen follows a flare guidance target also displayed on the screen.
Moreover, it should be noted that, due to the existence at airports of non-horizontal landing runways, i.e. having non-zero slopes, the flare maneuver must be capable of being adapted to landing runways of this type.
From document FR2.981.778, an automatic landing device of an aircraft, in particular a transport aircraft, is known which enables the implementation of an automatic landing on a landing runway having a high slope value.
However, this automatic device is not usable in all circumstances.
Similarly, the taking into account of a flare maneuver guidance signal based on information originating from such an automatic landing device is not optimal.
In fact, the flare guidance target (in accordance with a guidance signal of this type) typically moves on the screen by minimizing the deviation of the aircraft in relation to a reference flare trajectory. Due to this minimization, the system does not ensure a convergence of the guidance target toward a slope corresponding to a vertical speed required on contact with the landing runway. The use of a guidance symbol of this type originating from an autopilot to aid the pilot in performing the flare manually is therefore not optimal.